Pronunciation: (lit'yOO-us),[key] —n., —pl.lit•u•iPronunciation: (lit'yOO-ī").[key] 1. Geom.a polar curve generated by the locus of a point moving so that the square of its radius vector varies inversely as the angle the radius vector makes with the polar axis. Equation: θr2 = a. 2. (in ancient Rome) a crook-shaped staff used by augurs for divination.